Debugging a druntime issue found by AutoTester

[Ali Çehreli]

The automatic tests for a PR failed for a target that I could not test 
myself: 32-bit build on Darwin_64_32.

 
https://auto-tester.puremagic.com/show-run.ghtml?projectid=1&runid=2940199&dataid=20802787&isPull=true

Testing attach_detach
timelimit -t 10 ./generated/osx/debug/32/attach_detach
attach_detach(32762,0xb0103000) malloc: *** error for object 0x10000000: 
pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
make[2]: *** [generated/osx/debug/32/attach_detach.done] Error 134
make[1]: *** [test/thread/.run] Error 2
make: *** [unittest-debug] Error 2

How can I reproduce the issue perhaps on my Ubuntu-based 64-bit laptop? 
I'm hoping that the problem will be obvious if I can build a 32-bit 
target and "set a breakpoint in malloc_error_break to debug".

I tried to build a 32-bit dmd on my system but failed with dependency 
issues. Is the following right way?

$ MODEL=32 make -f posix.mak -j8 AUTO_BOOTSTRAP=1
[...]
/usr/bin/ld: skipping incompatible 
/usr/lib/gcc/x86_64-linux-gnu/5/libstdc++.so when searching for -lstdc++
/usr/bin/ld: skipping incompatible 
/usr/lib/gcc/x86_64-linux-gnu/5/libstdc++.a when searching for -lstdc++
/usr/bin/ld: cannot find -lstdc++
collect2: error: ld returned 1 exit status

Ali